The left in this country stole the term "liberal" in the 30's. Prior to the 30's, a "liberal" was like a "libertarian"--small government, low taxes, individual liberty. When the term "socialist" became unpopular because of association with the USSR, Germany and Italy, they decided to take over the term "liberal" and did so successfully.
What is less known and more insidious is that "Nazi" stands for "National Socialist Party". It doesn't take a lot of thought to realize that a revolutionary, totalitarian, anti-traditional, socialist, anti-Christian and dictatorial state isn't "conservative, libertarian or right wing" in any way. It is LEFT WING, and in fact prior to the holocaust discovery, the much of the left wing in this country revered both Hitler and Mussolini and vice-versa. Much of what both Hitler and Mussolini did was modeled on the Woodrow Wilson government in the US. Teddy Roosevelt, Wilson and FDR were all "progressives", which is close to "fascists". They were men of "collective action vs individual liberty".
Part of the confusion here is that the media and the left simply juxtaposes "facist, right wing, nazi, racist, militarist, evil, Republican, etc" in one tidy package and uses it for name calling, one of their favorite pastimes in lieu of rational discussion. Mussolini was certainly a totalitarian fascist-he created the term "totalitarian" to mean "the government takes care or your TOTAL life", but Mussolini was not anti-semitic or racist in other ways. Hitler was a fascist and he WAS racist. Franco was fascist and NOT racist. Racism is just another human problem, like flatulence, a fascist may have a problem with it, he may not. Same thing with Nationalism--Castro is very nationalist, but he would call himself a communist, as would most Americans.
Prior to the problems between Hitler and Stalin, there wasn't a lot of animosity between communism and fascism. Both were very much "workers parties", communism was just generally international, while fascism was generally nationalistic. The lefties of the world all correctly saw communism and fascism as pretty much the same thing -- heavier and heavier state control, less individual liberty, more collectivism, more central planning. When WWII happened, there was a rift between the USSR and Germany, so it tended to be couched in ideological terms. A lot of the book is spent on quotes and discussions from Teddy Roosevelt, Wilson, Mussolini, Hitler, Stalin and others showing that they were part of one big happy movement -- until they decided that a bad thing had happened in Germany, and they didn't want to be part of that. So, they picked the obvious scapegoat, "the right", even though there is nothing about "the right" that would lead one to think that "National Socialism" would be found there.
The book is 405 pages long, and the history of progressivism -> liberalism in this country and socialism, communism and fascism world wide is covered in a good deal of detail. The main point is NOT to say that "liberals are Nazis", although the cute little cover with the smiley face with Hitler mustache is certainly going to make liberals think that. Goldberg makes it clear in the book that fascist does NOT equal Nazi -- Fascist is pretty much "why can't we just get beyond politics, find a 3rd way, and let the smart experts do what needs to be done so we can we healthy wealthy and wise". That isn't evil, it is just dangerous ... because if you believe that can actually happen, you are already not thinking very straight, and if you think that the attempt at it isn't going to have a horrible cost in individual liberty, then you have been a grass munching sheep for way too long already.
I could quote and quote, but I'll leave with this one:
In America, a conservative is one who protects and defends what are considered liberal (old style) institutions in Europe but largely conservative ones in America: private property, free speech, free markets, individual liberty, freedom of conscience, and the rights of communities to determine for themselves how they will live within these guidelines. This is why conservatism, classical liberalism, libertarianism and Whiggism are different flags for the only truly radical political revolution in a thousand years. The American founding stands within this tradition, and modern conservatives seek to advance and defend it.